Currently, a great variety of catalytic converters is known, which catalytic converters are used to reduce emission of polluting gases derived from gasoline fueled internal combustion engines using lead-free or unleaded gasoline.
Catalytic converters use double bed and monolithic converter systems. Double bed systems are arranged in such a way that they have two zones of operation, where two types of catalytic material are located, in which reduction is conducted in the first section and oxidation in the second section. Monolithic converters may be oxidative, in which there is a need to add air to the system for its operation. Another type of this kind of converter is a three-way converter which is the latest and most effective, which operates without requiring additional air. The difference between these converters resides in their catalytic composition, since their internal structure is very similar.
Ceramic honeycomb catalytic converters are monolithic and contained in an exterior hollow body made of steel, generally stainless steel, which shape is similar to that of conventional exhaust pipes. In the converter is located a honeycomb shaped ceramic monolith with multiple and minute channels of diverse geometric and density of cells.
Such monoliths are fixedly located within a catalytic converter, which is installed in an automobile exhaust system in order to significantly reduce emission of such polluting gases.
Transition or noble metals have been used to impregnate ceramic supports covered with alumina, in order to obtain catalysts used for reducing emission of pollutants in gasoline engines. However, use of such catalysts have been restricted in use to only unleaded gasoline. Use of such catalysts with leaded gasoline causes the catalysts to become quickly inactivated. Thus, the operator is warned to use unleaded gasoline only. Accordingly, use of such catalysts with leaded gasoline is unpractical.
An object of the present invention is to provide a new process for the preparation of catalytically active ceramic monoliths useful for the reduction of pollutants derived from leaded gasoline-fueled internal combustion engines.
A further object of the invention is to provide a catalyst for reducing contaminating gases including hydrocarbons, carbon monoxide and nitrogen oxides.
Another object of the present invention is to provide a process for reducing emissions using a ceramic monolith catalyst.
Another object of the invention is to provide a ceramic monolith catalyst which can provide both high conversion in oxidation and reduction of pollutants.